Eyes Flashcards
Cornea vs pupil vs iris vs lens vs retina
protective layer that gathers and focus light vs absorbs light, regulates amount of light coming in vs adjust pupil size vs refracts and focuses light vs turns light into signals for brain, DOES NOT REFRACT OR FOCUS
Anterior chamber vs posterior chamber vs vitreous
lies in front of iris vs in b/w iris and lens vs behind lens that supports retina
Ciliary body vs canal of Sclemm vs ciliary muscle
produces aquaeous humor vs drains aq humor vs changes lens size
Describe the visual pathway
Cornea —> pupil —> anterior chamber —> iris —> posterior chamber —> lens —> retina –> optic nerves –> optic chiasm (where optic nerves cross & meet) –> optic tracts –> lateral geniculate nucleus –> temporal and parietal lobes –> visual cortex in occipital lobe. Basically everything in left visual field = processed by right side of brain and everything in right visual field = process by left side of brain
What is parallel processing? What’s parvo and magno pathway?
ability to simultaneously process color, shape and motion. Parvo - high spatial resolution and low temporal resolution –> detects shape of stationary things, can detect color; magno - high temporal resolution, low spatial resolution –> detects motion, can’t detect color
Where are retinal blood vessels vs choroid blood vessels?
in retina vs b/w sclera and retina
Phototransduction cascade
light hits 11-cis-retinal in rhodopsin in rod => all trans retinal –> rhodopsin changes shape –> alpha subunit of transducin binds to PDE –> turns cyclic GMP to GMP —> inc GMP closes Na channels –> hyperpolarization of cell –> rod turns off –> bipolar cell turns on
Constrictor and dilator pupillae
changes pupil size
Does the iris have photoreceptors?
No, only the retina does
What is the fovea?
Center of retina containing cones
What is it called when a lens is refocusing on an object? Does it thicken or flatten when focusing on a closer or farther object?
Accommodation via suspensory ligaments. Thickens for focusing on closer (ciliary muscles contract), flattens for focusing on farther (ciliary muscles relax)
Convergence vs mydriasis vs contrast
When eyes move toward one another to focus on very close up objects vs term for dilation of pupil vs diff in color and brightness
Extrinsic vs intrinsic eye muscles
For mechanical movement of eyeball like convergence, saccadic movements, tracking vs movement within the eye
What kind of lens do you need to fix myopia?
Concave diverging lens
Weber’s Law
Change in a stimulus that will be just noticeable is a constant ratio to orig stimulus
Duplexity or duplicity theory of vision
Retina contains 2 types of photoreceptors: rods and cones
amacrine and horizontal cells
vs bipolar cells vs ganglion cells
receive input from photoreceptors before passing them to bipolar and ganglion cells (they’re basically interneurons) vs highlight gradients between adjacent rods and cones vs with which bipolar cells synapse to form optic nerve (but bipolar cells don’t make up optic nerve, JUST GANGLION CELLS)
Which nervous system causes pupil dilation? How does pupil dilation affect focusing?
Sympathetic. Lets more light in, but harder to focus on closer objects
What are 3 types of photoreceptor cells?
rods, cones, and photosensitive retinal ganglion cells - don’t directly communicate visual info to brain, they’re involved in pupillary reflex
Presbyopia vs amblyopia vs strabismus vs nystagmus
Type of hyperopia (farsightedness), inability to focus vision of close-up objects vs one eye = communicating less visual info than other eye —> loss of vision in that eye —> brain learns to ignore visual stimulation of non dominant eye vs “lazy eye”, lack of coordination b/w extraocular muscles that orient eyes together in same direction, if not corrected —> non dominant eye will lose function, causes amblyopia vs condition of involuntary eye movements like eye shutter, doesn’t affect vision
Describe types of monocular cues
interposition - infers position, motion parallax/relative motion - when you’re moving, objects closer than your visual focus pt move opposite direction as you and objects farther from your visual focus pt move in same direction as you (ex: car vs moon), relative size - infers distance: if 2 objects = similar size then the smaller object = perceived farther away, relative height - infers distance: higher objects = perceived further while lower objects = perceived closer
